Observation of magnetic diffusion in the Earth's outer core from Magsat, Ørsted, and CHAMP data

Journal of Geophysical Research: Solid Earth

Volumn 115, Issue 5, 2010, Pages

  Chulliat, A ^a   Olsen, N ^b  

^a INSTITUT DE PHYSIQUE DU GLOBE DE PARIS   (France)

^b UNIVERSITY OF COPENHAGEN   (Denmark)

Author keywords

[No Author keywords available]

Indexed keywords

COMPUTER SIMULATION; CORE-MANTLE BOUNDARY; GEODYNAMO; GEOMAGNETIC FIELD; GEOMAGNETISM; MAGNETIC FIELD; MAGSAT; OUTER CORE; SATELLITE DATA;

EID: 77954385902     PISSN: 21699313     EISSN: 21699356     Source Type: Journal    
DOI: 10.1029/2009JB006994     Document Type: Article

References (49)

1. Allan, D. W., and E. C. Bullard (1966), The secular variation of the Earth's magnetic field, Proc. Cambridge Philos. Soc., 62, 783-809, doi:10.1017/ S0305004100040494.
2. Amit, H., and U. R. Christensen (2008), Accounting for magnetic diffusion in core flow inversions from geomagnetic secular variation, Geophys. J. Int., 175, 913-924, doi:10.1111/j.1365-246X.2008.03948.x.
3. Amit, H., P. Olson, and U. R. Christensen (2007), Tests of core flow imaging methods with numerical dynamos, Geophys. J. Int., 168, 27-39, doi:10.1111/j.1365-246X.2006.03175.x.
4. Aubert, J., J. Aurnou, and J. Wicht (2008), The magnetic structure of convection-driven numerical dynamos, Geophys. J. Int., 172, 945-956, doi:10.1111/j.1365-246X.2007.03693.x.
5. Backus, G. E. (1968), Kinematics of geomagnetic secular variation in a perfectly conducting core, Philos. Trans. R. Soc. London, Ser. A, 263, 239-266, doi:10.1098/rsta.1968.0014.
6. Bloxham, J. (1986), The expulsion of magnetic flux from the Earth's outer core, Geophys. J. R. Astron. Soc., 87, 669-678.
7. Bloxham, J., and D. Gubbins (1985), The secular variation of Earth's magnetic field, Nature, 317, 777-781, doi:10.1038/317777a0.
8. Bloxham, J., and D. Gubbins (1986), Geomagnetic field analysis-IV. Testing the frozen-flux hypothesis, Geophys. J. R. Astron. Soc., 84, 139-152.
9. Bloxham, J., and A. Jackson (1991), Fluid flow near the surface of Earth's outer core, Rev. Geophys., 29, 97-120, doi:10.1029/90RG02470.
10. Bloxham, J., D. Gubbins, and A. Jackson (1989), Geomagnetic secular variation, Philos. Trans. R. Soc. London, Ser. A, 329, 415-502, doi:10.1098/rsta.1989.0087.
11. Braginsky, S. I., and P. H. Roberts (1995), Equations governing convection in Earth's core and the geodynamo, Geophys. Astrophys. Fluid Dyn., 79, 1-97, doi:10.1080/03091929508228992.
12. Chulliat, A. (2004), Geomagnetic secular variation generated by a tangentially geostrophic flow under the frozen-flux assumption-II. Sufficient conditions, Geophys. J. Int., 157, 537-552, doi:10.1111/j.1365-246X. 2004.02216.x.
13. Chulliat, A., and G. Hulot (2001), Geomagnetic secular variation generated by a tangentially geostrophic flow under the frozen-flux assumption-I. Necessary conditions, Geophys. J. Int., 147, 237-246, doi:10.1046/ j.1365-246X.2001.00535.x.
14. Constable, C. G., R. L. Parker, and P. Stark (1993), Geomagnetic field models incorporating frozen-flux constraints, Geophys. J. Int., 113, 419-433, doi:10.1111/j.1365-246X.1993.tb00897.x.
15. Drew, S. J. (1993), Magnetic field expulsion into a conducting mantle, Geophys. J. Int., 115, 303-312, doi:10.1111/j.1365-246X.1993. tb05604.x.
16. Friis-Christensen, E., H. Lühr, and G. Hulot (2006), Swarm: A constellation to study the Earth's magnetic field, Earth Planets Space, 58, 351-358.
17. Gubbins, D. (1987), Mechanisms of geomagnetic polarity reversals, Nature, 326, 167-169, doi:10.1038/326167a0.
18. Gubbins, D. (1996), A formalism for the inversion of geomagnetic data for core motions with diffusion, Phys. Earth Planet. Inter., 98, 193-206, doi:10.1016/S0031-9201(96)03187-1.
19. Gubbins, D. (2007), Geomagnetic constraints on stratification at the top of the Earth's core, Earth Planets Space, 59, 661-664.
20. Gubbins, D., and P. Kelly (1996), A difficulty with using the frozen flux hypothesis to find steady core motions, Geophys. Res. Lett., 23, 1825-1828, doi:10.1029/96GL01392.
21. Gubbins, D., and P. H. Roberts (1987), Magnetohydrodynamics of the Earth's core, in Geomagnetism, vol.2, edited by J. Jacobs, pp. 1-183, Academic, London.
22. Gubbins, D., A. L. Jones, and C. C. Finlay (2006), Fall in Earth's magnetic field is erratic, Science, 312, 900-902, doi:10.1126/science.1124855. (Pubitemid 43727320)
23. Hide, R. (1978), How to locate the electrically conducting fluid core of a planet from external magnetic observations, Nature, 271, 640-641, doi:10.1038/271640a0.
24. Holme, R., and N. Olsen (2006), Core surface flow modelling from highresolution secular variation, Geophys. J. Int., 166, 518-528, doi:10.1111/ j.1365-246X.2006.03033.x.
25. Hulot, G., and A. Chulliat (2003), On the possibility of quantifying diffusion and horizontal Lorentz forces at the Earth's core surface, Phys. Earth Planet. Inter., 135, 47-54, doi:10.1016/S0031-9201(02)00191-7. (Pubitemid 36238419)
26. Hulot, G., C. Eymin, B. Langlais, M. Mandea, and N. Olsen (2002), Smallscale structure of the geodynamo inferred from Ørsted and Magsat satellite data, Nature, 416, 620-623, doi:10.1038/416620a. (Pubitemid 34406759)
27. Jackson, A. (1989), The Earth's magnetic field at the core-mantle boundary, Ph.D. thesis, Univ. of Cambridge, Cambridge, U. K.
28. Jackson, A., and C. C. Finlay (2007), Geomagnetic Secular Variation and Its Applications to the Core, in Treatise of Geophysics, vol.5, Geomagnetism, edited by M. Kono, pp. 147-193, Elsevier, Amsterdam, doi:10.1016/ B978-044452748-6.00090-0.
29. Jackson, A., C. G. Constable, M. R. Walker, and R. L. Parker (2007), Models of Earth's main magnetic field incorporating flux and radial vorticity con-straints, Geophys. J. Int., 171, 133-144, doi:10.1111/j.1365-246X. 2007.03526.x.
30. Jault, D. and J.-L. Le Mouël (1991), Physical properties at the top of the core and core surface motions, Phys. Earth Planet. Inter., 68, 76-84, doi:10.1016/0031-9201(91)90009-7.
31. Le Mouël, J.-L. (1984), Outer core geostrophic flow and secular variation of Earth's geomagnetic field, Nature, 311, 734-735, doi:10.1038/ 311734a0.
32. Love, J. J. (1999), A critique of frozen-flux inverse modelling of a nearly steady geodynamo, Geophys. J. Int., 138, 353-365, doi:10.1046/j.1365- 246x.1999.00895.x.
33. Lowes, F. (1966), Mean-square values on sphere of spherical harmonic vector fields, J. Geophys. Res., 71, 2179, doi:10.1029/JZ071i008p02179.
34. Maus, S. (2008), On the applicability of the frozen flux approximation in core flow modelling as a function of temporal frequency and spatial degree, Geophys. J. Int., 175, 853-856, doi:10.1111/j.1365-246X.2008.03972.x.
35. Maus, S., and P. Weidelt (2004), Separating the magnetospheric disturbance magnetic field into external and transient internal contributions using a 1D conductivity model of the Earth, Geophys. Res. Lett., 31, L12614, doi:10.1029/2004GL020232. (Pubitemid 39384102)
36. Maus, S., H. Lühr, M. Rother, K. Hemant, G. Balasis, P. Ritter and C. Stolle (2007), Fifth generation lithospheric magnetic field model from CHAMP satellite measurements, Geochem. Geophys. Geosyst., 8, Q05013, doi:10.1029/2006GC001521.
37. O'Brien, M. S., C. G. Constable, and R. L. Parker (1997), Frozen-flux modelling for epochs 1915 and 1980, Geophys. J. Int., 128, 434-450, doi:10.1111/j.1365-246X.1997.tb01566.x.
38. Olsen, N. (2002), A model of the geomagnetic field and its secular variation for epoch 2000 estimated from Ørsted data, Geophys. J. Int., 149, 454-462, doi:10.1046/j.1365-246X.2002.01657.x. (Pubitemid 34497696)
39. Olsen, N., T. J. Sabaka, and F. Lowes (2005), New parameterization of external and induced fields in geomagnetic field modeling, and a candidate model for IGRF 2005, Earth Planets Space, 57, 1141-1149.
40. Olsen, N., H. Lühr, T. J. Sabaka, M. Mandea, M. Rother, L. TØffner-Clausen and S. Choi (2006), CHAOS-A model of the Earth's magnetic field derived from CHAMP, Ørsted and SAC-C magnetic satellite data, Geophys. J. Int., 166, 67-75, doi:10.1111/j.1365-246X.2006.02959.x. (Pubitemid 43984352)
41. Olson, P., andH.Amit (2006), Changes in Earth's dipole, Naturwissenschaften, 93, 519-542, doi:10.1007/s00114-006-0138-6.
42. Rau, S., U. Christensen, A. Jackson, and J. Wicht (2000), Core flow inversion tested with numerical dynamo models, Geophys. J. Int., 141, 485-497, doi:10.1046/j.1365-246x.2000.00097.x. (Pubitemid 30309255)
43. Roberts, P. H., and G. A. Glatzmaier (2000), A test of the frozen-flux approximation using a new geodynamo model, Philos. Trans. R. Soc. London, Ser. A, 358, 1109-1121, doi:10.1098/rsta.2000.0576.
44. Roberts, P. H., and S. Scott (1965), On analysis of the secular variation, J. Geomagn. Geoelectr., 17, 137-151.
45. Sabaka, T. J., N. Olsen, and M. Purucker (2004), Extending comprehensive models of the Earth's magnetic field with Ørsted and CHAMP data, Geophys. J. Int., 159, 521-547, doi:10.1111/j.1365-246X.2004.02421.x. (Pubitemid 39520402)
46. Shure, L., R. L. Parker, and G. Backus (1982), Harmonic splines for geomagnetic modelling, Phys. Earth Planet. Inter., 28, 215-229, doi:10.1016/ 0031-9201(82)90003-90006
47. Takahashi, F., M. Matsushima, and Y. Honkura (2005), Simulations of a quasi-Taylor state geomagnetic field including polarity reversals on the Earth simulator, Science, 309, 459-461, doi:10.1126/science.1111831. (Pubitemid 40994682)
48. Wardinski, I., and R. Holme (2006), A time-dependent model of the Earth's magnetic field and its secular variation for the period 1980- 2000, J. Geophys. Res., 111, B12101, doi:10.1029/2006JB004401. (Pubitemid 47248709)
49. Whaler, K. (2007), Core motions, in Encyclopedia of Geomagnetism and Paleomagnetism, edited by D. Gubbins and E. Herrero-Bervera, pp. 84-89, Springer, Dordrecht, Netherlands.